slice:
eg:
>>>e=[0,1,2,3,4,5,6]
>>>s=slice(2,3)
>>>e[s]
[2]
slice的區間左閉右開[)
>>>s
slice(2,3,None)
slice([strar,]stop[,step]),start缺少時就是0
indices:
eg:
>>>print(s.indices(100))
(2,3,1)
>>>print(s.indices(3))
(2,3,1)
>>>print(s.indices(2))
(2,2,1)
>>>e[s]
[2]
這個indices相當於stop的位置,只要是大於之前的stop索引,按之前的來,否則就取小索引